Human Cytomegalovirus G Protein-Coupled Receptors

描述(申请人提供)：人类巨细胞病毒是贝塔疱疹病毒家族的典型成员。流行病学研究表明，人类巨细胞病毒感染广泛存在。在健康的人中，感染通常是无症状的，但该病毒可以在免疫系统不成熟或受损的人中导致严重疾病。它是导致出生缺陷的主要传染病原因，也是危及移植受者生命的外来病原体。这项研究计划的长期目标是阐明人类巨细胞病毒基因的功能，这些基因调节病毒与宿主细胞的相互作用，从而控制病毒的复制和发病。这一建议旨在帮助理解由HCMV编码的几个G蛋白偶联受体。其中一个待研究的受体是US28基因的产物。初步研究表明，缺乏US28编码区的突变型人巨细胞病毒在感染G0成纤维细胞后表现出基因加速表达的模式；在野生型病毒感染的成纤维细胞中，早期和晚期mRNAs在检测到它们之前就积累了很长时间。在缺乏US28受体的情况下，野生型病毒感染中观察到的即刻-早期、早期和晚期基因表达的时间依赖级联被破坏。第一个具体目的是研究编码人巨细胞病毒的pUS28在多种感染细胞中对转录级联的影响，并探讨pUS28的作用机制。第二个要研究的G蛋白偶联受体是UL78基因的产物。该基因的小鼠巨细胞病毒同源物被包装成病毒粒子，在通过病毒粒子包膜与质膜融合将受体传递到细胞后，它促进了病毒m123即刻早期基因的激活。在第二个特定目标中，不表达UL78产物的人巨细胞病毒突变体将在多种细胞类型中进行鉴定，以探索该受体的功能。该项目将包括分析人类巨细胞病毒的一个实验室毒株(AD169)和两个临床分离株(VR1814、FIX和PH)。病毒复制将在以下细胞中进行研究：常用于传播HCMV的成纤维细胞；与HCMV在动脉粥样硬化中可能扮演的角色相关的主动脉内皮细胞和平滑肌细胞；在病毒性视网膜炎中感染的视网膜色素上皮细胞；以及促进病毒传播的巨噬细胞。

DESCRIPTION (provided by applicant): Human cytomegalovirus is the prototypical member of the beta-herpes virus family. Epidemiological studies have shown that human cytomegalovirus infection is widespread. In healthy individuals infection is generally asymptomatic, but the virus can cause serious disease in people with immature or compromised immune systems. It is the leading infectious disease cause of birth defects and a life-threatening adventitious agent in transplant recipients. The long-term objective of this research program is to elucidate the function of human cytomegalovirus genes that regulate the interaction of the virus with its host cell and thereby control viral replication and pathogenesis. This proposal is designed to contribute to the understanding of several of the G protein-coupled receptors encoded by HCMV. One of the receptors to be studied is the product of the US28 gene. Preliminary studies have shown that a mutant human cytomegalovirus lacking the US28 coding region exhibits an accelerated pattern of gene expression after infection of G0 fibroblasts; early and late mRNAs accumulate long before they are detected in wild-type virus-infected fibroblasts. In the absence of the US28 receptor, the time-dependent cascade of immediate-early, early and late gene expression observed in wild-type virus infections is disrupted. The first specific aim seeks to characterize the effects of HCMV-coded pUS28 on the transcriptional cascade within multiple infected cell types and explore the mechanism of pUS28 action. The second G protein-coupled receptor to be studied is the product of the UL78 gene. The murine cytomegalovirus homologue of this gene is packaged into virions, and, after the receptor is delivered to cells by fusion of the virion envelope with the plasma membrane, it facilitates activation of the viral m123 immediate-early gene. In the second specific aim human cytomegalovirus mutants that do not express the UL78 product will be characterized in multiple cell types to explore the function of that receptor. This project will include analysis of a laboratory strain (AD169) and two clinical isolates (VR1814, FIX; and PH) of human cytomegalovirus. Viral replication will be studied in fibroblasts, the cell commonly used to propagate HCMV; aortic endothelial and smooth muscle cells, which are relevant to the possible role of HCMV in atherosclerosis; retinal pigmented epithelial cells, which are infected in viral retinitis; and macrophages, which facilitate virus spread.